In the current competitive market of consumer wireless mobile devices, power consumption and battery life are considered some of the most crucial factors for the product. Consequently, there has been extensive research on the subject of power reduction of wireless transceivers and it is currently a very active area of research. One of the recently explored concepts in this field is the zero-margin adaptive transceiver (ZMAT) paradigm. Typically, radio receivers are designed to meet the specifications of a particular wireless standard for the worst case wireless channel conditions. During use of the transceiver, however, most of the time the condition of the wireless channel is much better than the worst-case conditions. The ZMAT concept exploits such better channel conditions to save power, i.e. reduce the current consumption of one or more receiver components such as the low noise amplifier (LNA), mixer, filters, analog to digital converter (ADC), etc.
One of the dominating factors in characterizing the condition of the wireless channel is the signal to interference ratio (SIR). A low-IF (LIF) receiver is particularly affected by the interference at the image frequency, also referred to as the image signal. Typically, LIF receivers are designed with relatively high image rejection ratios (IRR) of approximately 40 to 60 dB. The required IRR is calculated according to the maximum tolerable image strength for the target wireless standard. The image strength, however, can vary over time and location and thus so does the IRR requirement.
There is thus a need for a radio receiver that extends the ZMAT concept to the rejection of image signals by providing image interference awareness. Such a radio receiver should identify and opportunistically exploit scenarios of very low image signal strength to significantly reduce power consumption of the radio receiver.